The Mucosal Immunology Core Laboratory (MICL) was first proposed and funded in 1998 due to an emerging awareness that mucosal lymphoid tissues were critically important as a reservoir for HIV infection. To our knowledge, this was the first Core facility of its kind in CFAR and continues to be a unique resource nationally. Interested researchers had little access to freshly acquired tissue and there were no validated assays for quantifying tissue HIV viral burden as well as other relevant mucosal immunologic and virologic markers. Since the start of the most recent CFAR renewal 4.5 years ago, the MICL has collected over 8000 mucosal tissue biopsies for study from 362 subjects. An additional 407 MICL encounters include 235 subject visits for screening, blood or semen donation without biopsies and 172 tissue specimens received from collaborators for assays or tissue specimens received from the Tissue Procurement Core Laboratory (TPCL). Also the MICL has supported 21 researchers (8 non-UCLA), 21 grant applications (16 funded), and during the past 2 years the MICL has developed a Clinical Trial Registry of 317 potential subjects for proactive recruitment as needed. This resource in unmatched anywhere and is a very unique CFAR resource for HIV investigators.